It screws in fine, but even when screwed down tight it leaks bad when the keg is pressurized. The previous pressure relief valve was getting sticky so I thought this would be a good idea. Just beware these are not compatible with all corny keg lids?

Nice and cheap. I replaced some questionable release valves with these and did not have a problem. If you suspect a leak from release valve or buy/obtain used sixtels I'd auto-replace with these. Good to have extra on hand.